Interventional procedures that are aided by images acquired during the procedures are well known. Such procedures have been reported utilizing almost every imaging modality. When taking biopsies, for example, a biopsy needle path is determined from an image of the region. During the insertion of the needle new or updated images are acquired and displayed to the physician to assure that the path is being followed or to allow for changes in the path as necessary.
For some procedures, especially those for which very accurate determination of needle path and position is necessary (for example, for brain biopsies) CT is an imaging modality of choice, since it provides superior and accurate representations of structure.
PCT publication WO 98/36690 describes a method and apparatus for efficiently producing updated images during an intervention procedure. Many other patents and other publications deal with CT systems useful for biopsy and other procedures.
However, despite the fact that such procedures are available on or easily implemented on existing CT imagers, they are not popular with physicians, apparently because the physicians hand (at least) is exposed to radiation during the procedure.